401(k) plan (Details Textual) (Plan 401 K [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Plan 401 K [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent	3.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 10

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration